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SECTION I 

 THE CLASSIFICATION OF TICKS. 



I. Historical Review of the Subject 1 . 



Although the classification of ticks may be considered as dating 

 from Linnaeus (1746, p. 479), who included them under Acari in the 

 large genus Acarus, scientific nomenclature did not actually commence 

 until the time of Latreille. This author (1795, p. 15) called the 

 Acari " tiques " and divided them into 11 genera of which two were 

 Argas and Ixodes. Later (1804, p. 46) he included these two genera 

 with five others (Sarcoptes, Uropoda, etc.) under Riciniae. Hermann 

 (1804, p. 63) included Rhynchoprion (Argas) and Cynorhaestes (Ixodes) 

 under Acarina, but kept them far apart, not recognizing their close 

 relationship. Leach (1815, p. 387) called the Acarina Monomer osomata., 

 and divided them into 11 families, one of which, Ixodides, included 

 Argas, Ixodes and Europoda. He was succeeded by von Heyden 

 (1826, p. 608), who upset previous classifications and again separated 

 Argas from Ixodes. Sundevall (1833) divided the Acari into six 

 families, one of which, Ixodides, included ticks only, viz. Argas and 

 Ixodes. Duges (1834, p. 5) divided the group into seven families, one 

 of which, Ixodei, included Ixodes, and Gamasei included Argas. 



C. L. Koch (1844, p. 220 ; 1847, p. 13) ranked ticks in a special order 

 distinct from the Acari, naming the order Ricini, which included three 

 families: 1. Argasiden (Argasides, in English, with two genera: Argas 

 and Ornithodoros) ; 2. Ixodiden (Ixodides, in English, with four genera : 

 Hyalomma, Haemalastor, Amblyomma and Ixodes) ; and 3. Rhipi- 

 stomiden (with four genera : Dermacentor, Haemaphysalis, Rhipistoma 

 and Rhipicephalus) ; families 2 and 3 were distinguished from each 

 other by the possession of long and short palps respectively. Koch's 

 classification was generally adopted by subsequent authors, and has 



1 A number of classical authors refer to ticks. See Bibliography under Aristotle, 

 Cato, Varro, Columella, Pliny, Sammonius, Aldrovandi. 



N. I. 8 



